This invention relates to a snap-in lamp terminal for wedge-base bulbs used in an assembly with a wedge-base bulb socket. The invention improves electrical contact between the bulb and terminal and allows the terminal to be used in a socket housing made from soft vinyl material.
Components of the socket assembly are the wedge-base bulb, the snap-in lamp terminal, the snap-in tubular socket or, when situations demand, the vinyl socket housing. Their descriptions follow.
The wedge-base bulb is made up of a bulbular evacuated chamber fused to a wedge-base. The wedge-base configuration includes a raised centrally located cylindrical vent tube running along the central longitudinal axis of the bulb. The vent tube is bound on both sides by laterally extended side wings. The bulb also has a lamp filament wire which extends through and out the bottom end of the side wings in such a manner that on either side of the vent tube there is only one end of the filament wire. Each end is bent or looped back upon itself and reentrant in and sealed in the wedge-base. This looped formation is then bent back onto the wedge-base extending towards the bulbular evacuated chamber, one looped wire on the front of the wedge-base, the other on the back side. The wedge base also has two concave detent troughs extending transversely to the longitudinal axis of the bulb. Each detent trough is located on the opposite side of the side wing where the filament wire extends. Thus, on one side of the wedge-base on the side wing, left of the vent tube, the filament wire loop extends toward the bulbular evacuated chamber. On the side wing to the right of the vent tube is the transversely extending detent trough.
The next component of the socket assembly is the snap-in lamp terminal. The snap-in lamp terminal is made up of a channel shaped body, extending longitudinally, surrounding contact arms attached to each side. The front entry-way of the terminal has a wire guide protruding from one side of the channel body. The rear of the terminal has a mold fill retention wall to allow the terminal to be molded directly into a vinyl socket. This wall is only necessary when a vinyl socket assembly is made by injecting vinyl material into a mold with the terminals present.
Located inside the terminal channel body is a redundant contact terminal means (to be explained later).
The socket assembly designed for the wedge-base bulb then consists of a pair of snap-in lamp terminals held either by a molded vinyl lamp socket or a hard tubular snap-in lamp socket. The tubular socket has an interior rib dividing the interior of the socket into two longitudinally extending channels. These channels accept the snap-in lamp terminals and hold them in place by a cantilevered wedge clamp running along the outside longitudinal axis of the tubular socket. Upon insertion of the terminals, the socket assembly, now complete, is ready for the installation of the wedge-base bulb.
The wedge-base bulb is axially inserted into the front of the socket assembly and makes electrical contact with the terminals which allows for energization of the bulb. This electrical contact is accomplished through the surface contact of the bulb's filament wire and the terminal's contact arm. Specifically, upon installation of the bulb, the wedge base is squeezed by the two contact arms of the terminal. One contact arm exerts spring pressure on the side wing of the bulb where it interlocks with the detent trough. The other contact arm exerts spring pressure on the opposite side of the same side wing where it makes electrical contact with the bulb's filament wire. This electrical contact is made only if the filament wire is in its proper mating position. That proper position is between the exterior edge of the side wing and the edge of the central vent tube where the wire extends towards the bulbular evacuated chamber parallel with the longitudinal axis of the bulb.
Often, the filament wire is not in this correct mating position due to the manufacturing and handling process. When such occurs, the wedge-base bulb must be manually removed from the socket and the filament wires manually straightened to provide proper electrical contact upon re-installation of the bulb.
To provide for better filament wire positioning, not through costly manual means, but by utilizing an alignment device upon insertion of the bulb, a wire guide means was introduced into previous terminal designs. This wire guide means protrudes out toward the center of the terminal channel and wipes near the surface of the vent tube. This wiping action was designed to realign a filament wire skewed onto the middle of the wedge-base extending across the body of the vent tube. Realignment occurs when the wire guide interferes with the filament wire and pushes it back to its proper mating position. Alignment of skewed filament wires protruding toward the exterior edge of the side wing occurs by interference with the terminal base. This interference urges the skewed filament wire back to its proper mating position.
The wire guide in some cases cannot reach extremely skewed filament wires and the terminal base cannot align skewed filament wires to the extreme outer edge of the side wing. Because of these extremely skewed filament wires, a wedge-base bulb might light intermittently or possibly not at all and a costly manual realignment of the filament wires becomes necessary.
The preferred embodiment urges better electrical contact upon installation. The subject invention provides a wire guide which wipes onto and not near the surface of the vent tube urging better alignment for even extremely skewed filament wires onto the vent tube.
The subject invention also provides a redundant contact terminal means whereby a skewed filament wire, not properly aligned by the improved wire guide or the terminal base, will still be urged to make proper electrical contact by providing a second contact surface in the interior of the terminal channel.
Previously designed snap-in lamp terminals were restricted in their utility because they could not be molded into vinyl without costly manufacturing provisions to prevent the vinyl mold fill from leaking into the terminal channel and insulating the electrical contact arms. The preferred embodiment remedies this problem by providing a wall in the rear of the terminal which will stop the flow of the vinyl mold fill into the interior of the terminal channel. This provision allows the preferred embodiment to be molded directly into the vinyl socket providing a less costly water resilient vinyl socket.
It is, therefore, an object of the invention to provide a snap-in lamp terminal for wedge-base bulbs with improvements in the wire guide design to urge proper alignment of the filament wires of the bulb which may be skewed onto the central vent tube.
Another object of the invention is to provide a redundant contact terminal means to urge proper electrical contact should the terminal base or the improved wire guide fail to realign the filament wire to its proper mating position. This redundant contact terminal means is demonstrated in the invention showing the snap-in lamp terminal incorporating four different structures of the redundant contact terminal means.
Still another object of the invention is to incorporate a mold fill retention wall in the rear of the teminal so that the snap-in lamp terminal can be used with a soft vinyl filled socket without flow of the mold material into the interior of the terminal.
These and other objects and advantages of the snap-in lamp terminal with redundant contact terminal means, improved wire guide and mold fill retention wall will become apparent from the following Detailed Description of the Preferred Embodiment, Drawings and Claims.
This application is one of six applications filed on July 3, 1985, all commonly assigned and having substantially the same Specification and Drawings, the six applications being identified below:
______________________________________ U.S. Serial Number Title ______________________________________ 751756 Snap-In Terminal With Wire Guide 752264 Cantilevered Redundant Terminal 752328 Tab Redundant Terminal 752265 Folded Redundant Terminal 752411 Base Redundant Terminal 752202 Mold Fill Retention Wall For Snap-In Terminal ______________________________________